21241265 has 4 divisors (see below), whose sum is σ = 25489524. Its totient is φ = 16993008.

The previous prime is 21241261. The next prime is 21241271. The reversal of 21241265 is 56214212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2999824 + 18241441 = 1732^2 + 4271^2 .

It is a cyclic number.

It is not a de Polignac number, because 21241265 - 2² = 21241261 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21241265.

It is not an unprimeable number, because it can be changed into a prime (21241261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2124122 + ... + 2124131.

It is an arithmetic number, because the mean of its divisors is an integer number (6372381).

Almost surely, 2^21241265 is an apocalyptic number.

It is an amenable number.

21241265 is a deficient number, since it is larger than the sum of its proper divisors (4248259).

21241265 is an equidigital number, since it uses as much as digits as its factorization.

21241265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4248258.

The product of its digits is 960, while the sum is 23.

The square root of 21241265 is about 4608.8246874881. The cubic root of 21241265 is about 276.9449555463.

Adding to 21241265 its reverse (56214212), we get a palindrome (77455477).

The spelling of 21241265 in words is "twenty-one million, two hundred forty-one thousand, two hundred sixty-five".